The present invention relates to electroplating barrels, and in particular to a design for a barrel having side panels and an access door with an improved locking mechanism utilizing a unique combination of support ribs and elongated perforations which encourage efficient circulation of the electroplating solution.
The use of polygonal shaped barrels, and particularly hexagonal shaped barrels is well known in the prior art. These barrels generally include an access point on one side of the barrel for putting the material to be electroplated into the barrel and then removing it after the process has been completed. This process is usually accomplished by dipping the barrel into a bath of electroplating solution and then running an electric current through the barrel while rotating the barrel on an axis.
The passage of the solution into the barrel has generally been accomplished by either the use of a chemically inert mesh fabric as seen in U.S. Pat. No. 3,472,753, or through the use of small circular or square perforations in a solid chemically inert panel as seen in U.S. Pat. Nos. 3,936,985 and 5,639,306.
However, these barrels have been generally used in an industrial setting where rough handling is commonplace and the barrels must repeatedly sustain such treatment. As a consequence the mesh design was unable to effectively deal with these repeated stresses. This problem has been addressed by utilizing a combination of rib segments where at each intersection one such segments ends with the small circular perforation discussed above as seen in U.S. Pat. No. 5,639,306.
However, in that device, along with all other prior art, the problem of maintaining efficient circulation of electroplating solution while minimizing the capillary effect, also known as xe2x80x9cdrag-outxe2x80x9d, produced through the utilization of circular openings has played a secondary role to the maintenance of the structural stability of the barrel. Considering that problem, it is an object of the present invention that the xe2x80x9cdrag-outxe2x80x9d of solution is minimized while the barrel still possesses a rib structure and door locking mechanism that can withstand the rigors of a manufacturing environment.
It is another object of the invention to utilize a support rib structure and door locking mechanism that will withstand the rigors of manufacturing while increasing the circulation of electroplating solution in the electroplating tank, thus increasing efficiency of the electroplating process.
It is a further object of the invention to design a side panel which will allow for easy replacement and introduction into the manufacturing environment.
This invention comprises a rotatable barrel for holding objects to be electroplated having at least one perforated side panel that permits the efficient transfer of electroplating solution into and out of the barrel with minimal xe2x80x9cdrag outxe2x80x9d effect. The design of the side panel includes a base along with a support rib structure that defines sections of the panel that are the shape of a parallelogram. Within the parallelogram shaped section are elongated and cross segments that define elongated perforations, which allow the solution to enter and exit the barrel while retaining the electroplated pieces inside. The barrel preferably is constructed of a chemically inert material. The interior of the barrel, that is the side of the panel opposite the ribs can, be either smooth or uneven.
The support ribs run generally in the direction of the length and the width of the panel but with the ribs laid out so that the intersection points of the ribs always form complementary obtuse and acute angles with each other. The side of the panel opposite the ribs can be either smooth or uneven. In one embodiment the lengthwise ribs, also called longitudinal ribs, run parallel with the length edge of the panel, while the width ribs, also called cross ribs, run approximately 20xc2x0 from parallel with the width edge of the panel. In another embodiment this arrangement could be switched so that the cross ribs run parallel with the width edge and the longitudinal ribs are angled to create the parallelogram shape. Increasing or decreasing the angle of the cross ribs could also modify the arrangement.
Circulation of the electroplating solution within the bath and the barrel has previously been directed by the rotation of the barrel in the bath. This rotation encouraged circulation only in primarily one direction. The angled arrangement of the ribs in this invention increases this circulation by directing the flow of the solution into and out of the barrel at an angle corresponding to the angle of the cross ribs. This creates a multi-directional circulation pattern within the tank and the barrel that corresponds to an increase in efficiency of electroplating. This efficiency is further enhanced by the utilization of access doors with an improved locking mechanism that enables the access doors to share an identical type of support rib structure.
This increase in circulation is also affected by the arrangement of the perforations within the parallelogram shaped sections. Prior barrels designs have generally utilized small square or circular holes through which the electroplating solution can pass into and out of the barrel, which, even when utilizing thin perforated plates, can lead to a large xe2x80x9cdrag outxe2x80x9d of solution when the barrel is removed from the bath. The current invention reduces this xe2x80x9cdrag outxe2x80x9d by increasing the size of the perforations so that less solution will remain. As the size of the perforations increases the likelihood of solution remaining trapped within the perforations decreases since it is more likely that the surface tension of the solution holding the solution to the opening will be overcome by gravity in the larger area.
In the past these perforations have always been small and usually circular due to concerns of the strength of the panel wall. This invention utilizes support segments arranged generally parallel to each other that define a pattern of rows of elongated openings. The elongated openings serve two purposes: 1) they decrease the xe2x80x9cdrag outxe2x80x9d effect through their larger volume and 2) they increase the circulation of electroplating solution within the barrel by having the elongated perforations run parallel with one of the two directions of ribs. In another embodiment the support segments are interconnected by cross segments that serve to further strengthen the parallelogram shaped section.
It is the combination of these elements, the parallelogram shaped sections defined by support ribs and the parallel running elongated perforations within the parallelogram sections, that enable this invention to be the most efficient. However, either on their own are enough to increase efficiency of the electroplating process.
Furthermore, the barrel in this invention utilizes an improved door locking mechanism utilizing a crossbar with locking spherical rollers that enable the crossbar to be moved and secured into locked and unlocked positions. This removable door also utilizes the abovedescribed parallelogram shaped sections with elongated openings to increase electroplating solution circulation within the barrel.